I thought that this case was a difficult one. The California Supreme Court had a slightly different take, and unanimously reverses and remands.
That said, the really hard part remains whether the Double Jeopardy Clause bars a retrial. And the California Supreme Court seems to agree with me that that one ain't at all clear. It doesn't decide the issue. Remanding for the Court of Appeal to decide the matter in the first instance.
And that's the toughie.